Image color change when upgrading from LR 6 to LR Classic

I'm getting a really wierd problem with image appearance having upgraded from LR 6 to LR Classic. When I open images previously processed in LR 6 they have a green cast. The images were processed with Camera Standard profile. If I change the profile to Adobe Color & then back to Camera Standard the problem goes away.

On first opening an image with green cast the color temp & tint are 4400, -30, which matches that shown in LR 6. Having corrected the image by cycling the profile the temp & tint change to 5750, -3.

I'm running on a Windows 10 PC.

I would appreciate any help with overcoming this as the thousands of images in my catalog are all coming out with this problem.